Heat oil in a large stockpot over medium-high heat. Add onion, carrots and celery. Saute for 7 minutes, stirring occasionally, until the onion is soft and translucent. Add garlic and sautee for an additional minute or two until fragrant.

Add in remaining ingredients, and stir to combine. Use a long spoon to crush the tomatoes. Bring to a boil, then reduce heat to medium-low and simmer partially-covered for 10 minutes. Season with additional salt and pepper if needed.

Serve with freshly-grated Parmesan cheese.

**Or, you can add all ingredients except the cheese to a slow cooker, stir to combine, cook on high for 3-4 hours (or low for 6-8), then serve with freshly-grated Parmesan cheese.**

In a Dutch oven or deep pot, layer ingredients, bottom to top Potatoes, carrots, cabbage, scallions. Cover the potatoes and carrots with cold water, just enough to cover potatoes and carrots. The other vegetables will steam during cooking to desired tenderness. Add salt to taste.

Bring to a boil, then reduce heat to maintain a gentle simmer. Cook, covered until potatoes are near fork-tender, carrots crispy tender, about 15-20 minutes. Drain and return all ingredients to pot.

Mash the mixture while adding butter and parsley. The potato mixture should be coarsely mashed & thick. Add milk for thinning if desired. Serve hot with sliced corned beef.